1. Field of the Invention
The present invention relates to a toner cartridge for an electrophotographic printer or the like, and more particularly to a toner cartridge comprising an outer cylinder and an inner cylinder which is slidably contained in the outer cylinder.
2. Description of the Prior Art
There is known a toner cartridge comprising an outer cylinder having outer cylinder apertures formed at opposite ends thereof and an inner cylinder contained in the outer cylinder in such a relation that it is adjacent to the outer cylinder and rotatably slidable relative thereto, which inner cylinder has inner cylinder apertures formed at opposite ends thereof. Such a conventional toner cartridge is shown in FIGS. 8-12.
As is apparent from FIGS. 8 and 9, the conventional toner cartridge is so arranged that an outer peripheral surface of an inner cylinder 7, including an inner cylinder rib 10, and an inner peripheral surface of an outer cylinder 2, including an outer cylinder rib 6, are relatively slidable over the entire peripheries thereof.
Referring to FIGS. 8 and 10, inner cylinder toner discharge openings 9 are closed by an inner wall of the outer cylinder 2. Thus, toner (not shown) filled into the inner cylinder 7 is not discharged therefrom. If it is required to discharge the toner from outer cylinder toner discharge openings 5, the inner cylinder 7 is slidably rotated relative to the outer cylinder 2 in the direction of an arrow A so that the inner cylinder toner discharge openings 9 are aligned partially with the outer cylinder toner discharge openings 5. If inner cylinder 7 is further rotated relative to the outer cylinder 2 in the direction of arrow A, the inner cylinder toner discharge openings 9 are aligned fully with the outer cylinder toner discharge openings 5, as shown in FIGS. 11-12, whereby there is obtained a fully opened condition. In such a condition, inner cylinder rib 10 is aligned with outer cylinder rib 6. If it is required to close the inner cylinder toner discharge openings 9, the inner cylinder 7 is rotated relative to the outer cylinder 2 in the direction of arrow B in FIG. 12, such that the inner cylinder toner discharge openings 9 are closed by the inner wall of the outer cylinder 2.
However, there is a problem with this toner cartridge arrangement. If the inner cylinder 7 or the outer cylinder 2 are deformed, it will be impossible to achieve a smooth sliding motion between the outer peripheral surface of the inner cylinder 7 and the inner peripheral surface of the outer cylinder 2, and such a deformation will lead to galling due to interference between such surfaces. Further, the conventional toner cartridge is so arranged that outer peripheral surfaces at opposite ends of the inner cylinder 7 and inner peripheral surfaces at opposite ends of the outer cylinder 2 are relatively slidable over the entire peripheries thereof. There also is a problem with this arrangement. If the outer cylinder 2 is deformed, it will be impossible to achieve a smooth sliding motion between the outer peripheral surfaces at opposite ends of the inner cylinder 7 and the inner peripheral surfaces at opposite ends of the outer cylinder 2, and such a deformation will lead to galling due to interference between such surfaces.
Furthermore, the conventional toner cartridge is so arranged that edges 9a of the inner cylinder toner discharge openings 9 and edges 5a of the outer cylinder toner discharge openings 5 are in parallel relation. There is a problem with this arrangement in that when the inner cylinder toner discharge openings 9 are closed, the respective edge portions may be overlapped. Thus, it may be impossible to fully close the inner cylinder toner discharge openings 9.